Details:

Journal Title:
Journal of Climate
Personal Author:
Luo, Dehai ; Yao, Yao ; Dai, Aiguo ; Simmonds, Ian ; Zhong, Linhao
Luo, Dehai ; Yao, Yao ; Dai, Aiguo ; Simmonds, Ian ; Zhong, Linhao Less -
Corporate Authors:
United States. National Oceanic and Atmospheric Administration. Office of Oceanic and Atmospheric Research ; Modeling, Analysis, Predictions, and Projections Program (U.S.)
United States. National Oceanic and Atmospheric Administration. Office of Oceanic and Atmospheric Research ; Modeling, Analysis, Predictions, and Projections Program (U.S.) Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research) ; CPO (Climate Program Office)
OAR (Oceanic and Atmospheric Research) ; CPO (Climate Program Office) Less -
Description:
In Part I of this study, it was shown that the Eurasian cold anomalies related to Arctic warming depend strongly on the quasi stationarity and persistence of the Ural blocking (UB). The analysis here revealed that under weak mean westerly wind (MWW) and vertical shear (VS) (quasi barotropic) conditions with weak synoptic-scale eddies and a large planetary wave anomaly, the growth of UB is slow and its amplitude is small. For this case, a quasi-stationary and persistent UB is seen. However, under strong MWW and VS (quasi baroclinic) conditions, synoptic-scale eddies are stronger and the growth of UB is rapid; the resulting UB is less persistent and has large amplitude. In this case, a marked retrogression of the UB is observed.

The dynamical mechanism behind the dependence of the movement and persistence of UB upon the background conditions is further examined using a nonlinear multiscale model. The results show that when the blocking has large amplitude under quasi-baroclinic conditions, the blocking-induced westward displacement greatly exceeds the strong mean zonal-wind-induced eastward movement and hence generates a marked retrogression of the blocking. By contrast, under quasi-barotropic conditions because the UB amplitude is relatively small the blocking-induced westward movement is less distinct, giving rise to a quasi-stationary and persistent blocking. It is further shown that the strong mid–high-latitude North Atlantic mean zonal wind is the quasi-barotropic condition that suppresses UB’s retrogression and thus is conducive to the quasi stationarity and persistence of the UB. The model results show that the blocking duration is longer when the mean zonal wind in the blocking region or eddy strength is weaker.


Keywords:
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Blocking (Meteorology) Climatic Changes Climatic Extremes Models Nonlinear Oscillations Sea Ice Variability Climate Variability Extreme Events Nonlinear Models
Source:
Journal of Climate, 30(10), 3569-3587.
DOI:
https://doi.org/10.1175/JCLI-D-16-0262.1
Document Type:
Journal Article
Funding:
Grant no. NA15OAR4310086
Rights Information:
Other
Compliance:
Submitted
Main Document Checksum:
[+]
urn:sha256:d663e67ca2b583611493e7521c03dd5845aa0ae8f1bfe6b3fefc36feded21f87
Download URL:
https://repository.library.noaa.gov/view/noaa/28399/noaa_28399_DS1.pdf
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